CAMP PENDLETON, Calif. — After a decade fighting two wars and in the midst of a shrinking military in transition, Marine expeditionary units and their amphibious ready groups deployed at sea remain the nation’s premier crisis-response team.

But after that initial assault or humanitarian support, Marine expeditionary brigades and naval expeditionary strike groups will most likely take on the role of combining capabilities to expand and sustain those operations.

Supporting the brigade-size force of Marines and sailors ashore beyond the initial stages of operations, however, will depend much on Marine Corps combat gear maintained round-the-clock on the Navy’s fleet of maritime prepositioning ships. But getting those war stocks of combat equipment, vehicles, supplies and spare parts off the ships and in the hands of Marines and sailors is no easy job.

In fact, it’s a skill to coordinate delivery of the right equipment where it’s most needed and at the right time to meet commanders’ operational needs on the ground in a changing, dynamic operational environment. Think natural disaster turns into humanitarian mission interrupted by civil strife.

Such scenarios were among the backdrop to major planning and training drills during the Pacific Horizon 2012 exercise held here Sept. 10-14.

The tabletop planning exercise with 1st Marine Expeditionary Brigade and Expeditionary Strike Group 3 tested headquarters staffs and subordinate units in the command and control of a brigade-sized force through a rapidly changing operational scenario, which required more combat equipment and forces be brought in theater. That requires tapping into the war stores held by maritime prepositioning force, or MPF, ships.

But a smooth operation is never guaranteed. Senior leaders say that when crises pop up isn’t the time Marines and sailors, along with their senior commands, must figure out how to use and maximize at-sea prepositioned stocks.

The Marine Corps hasn’t done an MPF operation as part of larger-scale training exercises for more than a decade, and maritime prepositioning wasn’t part of Bold Alligator, U.S. Fleet Forces Command’s large amphibious exercise held off Virginia earlier this year.

“There’s a lot of work we need to do to make sure we are ready to get equipment off of the ships and respond to a mission,” said Maj. Gen. Melvin Spiese, the 1st MEB commander at Pendleton. “That’s the hard part.”

The Navy has three MPF squadrons based at Diego Garcia in the Indian Ocean; Guam in the Pacific Ocean and Naples, Italy, in the Mediterranean. Each squadron has ships equipped with equipment and supplies to sustain a 15,000-member Marine air-ground task force for up to 30 days — the idea is to sustain the initial entry force.

The ships provide the combat equipment and gear needed for those larger forces flown into the theater to augment the initial force — most likely a MEU/ARG at sea. Their roll-on, roll-off capability lets vehicles and equipment be offloaded quickly, even in remote or stark places lacking a seaport. Most any beach or shoreline will do.

It’s not just offloading needed items from a ship, but getting the right pieces of equipment and supplies where and when they are needed by forces that may arrive in theater in larger numbers — and “it can be [while] fighting our way into position,” said Spiese.

Saving a ‘perishable skill’

Rear Adm. Gerard Hueber, the ESG 3 commander in San Diego, said it’s “vitally important” for the senior leaders and their commands to come together and integrate in practicing these missions, much like ARG/MEUs do at that level during their integrated predeployment training exercises.

Along with the tabletop exercise, ESG 3 is incorporating more training and professional military education for its planners and other staff members leading up to the large-scale amphibious Dawn Blitz exercises next year off California.

The ability to plan and execute brigade-level operations with an MPF mission “is a perishable skill,” Hueber said.

But, said Spiese, “many Marines haven’t done this.”

This month’s Pacific Horizon exercise is the latest in a series of brigade-level training exercises that 1st MEB and ESG 3 began in 2011. Operational demands and wartime deployments have limited the availability of getting hands on a real MPF ship. No MPF ship joined in this year’s Pacific Horizon training, but officials say that will change next year with Dawn Blitz exercises, to be held off San Diego and Camp Pendleton in January and June.

In the Pacific Horizon training exercise held in March 2011, Marines and sailors practiced an in-stream offload of equipment to the beach at Camp Pendleton from roll-on/roll-off ship Button and aviation logistics support ship Curtiss.

In July 2011, more than 5,000 Marines, including reservists and a Canadian headquarters brigade, joined in live-fire combined-arms training at Marine Corps Air-Ground Combat Center at Twentynine Palms, Calif. That exercise, Javelin Thrust, served as the land component of the Dawn Blitz continuum, Langley said.